Ubuntu 16.04陷入启动循环，执行sudo apt-get update后无法登录求助

Alright, let's dig into this frustrating GNOME login loop issue you're dealing with after running sudo apt-get update and rebooting. It sounds like the update might have borked some core GNOME components, display drivers, or user configs—let's walk through some targeted fixes that go beyond the usual generic solutions:

• First, access the TTY terminal (since the graphical login is broken):
  Press Ctrl+Alt+F3 (or any F key from F2 to F6) to switch to a text-based terminal. Log in with your username and password—this will let you run commands without the graphical interface.

• Repair broken packages
  Updates sometimes get interrupted or leave packages in a broken state. Run these commands in sequence:

  sudo apt-get install --fix-broken
  sudo dpkg --configure -a
  sudo apt-get update && sudo apt-get upgrade -y
  

  Reboot after this with sudo reboot and try logging in again.

• Reset your GNOME user configuration
  Corrupted user config files are a common culprit for login loops. Let's back up your current config and reset it:

  mv ~/.config/dconf/user ~/.config/dconf/user.bak
  mv ~/.gconf ~/.gconf.bak
  

  Reboot with sudo reboot—this will force GNOME to create fresh default configs.

• Reinstall GNOME Shell and core components
  If the update damaged GNOME's core files, reinstalling them might fix the issue:

  sudo apt-get install --reinstall gnome-shell gnome-session gdm3
  

  Reboot and test the login again.

• Check for display driver conflicts
  Updates often break proprietary display drivers (like NVIDIA). Let's switch to the open-source Nouveau driver to test:

  # Uninstall all NVIDIA-related packages
  sudo apt-get purge nvidia* -y
  # Install open-source Nouveau driver
  sudo apt-get install xserver-xorg-video-nouveau -y
  # Update initramfs to apply changes
  sudo update-initramfs -u
  

  Reboot and see if you can log in. If this works, you can later try reinstalling the latest compatible proprietary driver once the system is stable.

• Disable GNOME extensions
  Third-party extensions are frequently incompatible after system updates. Disable all extensions from the TTY:

  gnome-extensions disable --all
  

  Reboot and test—if you can log in, you can re-enable extensions one by one to find the problematic one.

• Test with a new user account
  If none of the above works, create a temporary user to rule out user-specific config issues:

  sudo adduser testuser
  

  Reboot and try logging in as testuser. If this works, the problem is isolated to your original user's config—you can either migrate your files to the new user or debug the corrupted configs further.

If you're still stuck, check the system logs for specific error details to narrow down the issue:

journalctl -b -p err

This will show critical errors from the current boot—look for entries related to gnome-shell, gdm3, or Xorg, which will give you more clues about what's failing.

内容的提问来源于stack exchange，提问作者9voltWolfXX